SU958847A1 - Device for measuring dimensions of flat surfaces - Google Patents

Description

(54) DEVICE FOR MEASURING DIMENSIONS OF FLAT SURFACES

. one

The invention relates to instrumentation technology and can be used, in particular, to measure the dimensions (length, width or area) of flat surfaces of arbitrary shape.

Resistive displacement sensors are known for measuring dimensions that contain an ohmic element (reohord) with a moving contact that is associated with the object being monitored during measurement 1.

Their disadvantage is the presence of a sliding contact.

Closest to the present invention is a device for measuring the dimensions of flat surfaces, comprising a resistive sensor and a measuring circuit in which this sensor is included. The sensor in this device is made in the form of a wire from a high-resistance material wound in a spiral manner on an elastic base. The helix cuts are cut from one side so that they are not closed between each other. Above the helix there is an elastic conductive material with a dielectric wear-resistant coating. Each turn of the helix is connected at one end to the measuring circuit, which provides measurement of the resistance of those coils, the helix, which are closed between themselves through a conductive material while pressing it to the corresponding part of the helix by an object whose surface area is measured 2.

The disadvantages of the sensors are the limited accuracy of measurements, due to the relatively large pitch of the high wire, and the ability to measure with a given accuracy of dimensions and area of surfaces that have only a regular geometric shape.

The purpose of the invention is to improve the measurement accuracy and expand the range of the monitored surfaces, i.e. enabling measurement with a given accuracy of the surface area of an arbitrary shape.

Claims (2)

This goal is achieved by the fact that in a device for measuring the dimensions of flat surfaces containing a resistive sensor and a measuring circuit, the resistive sensor is made in the form of a flat U-shaped zigzag of high-resistance material deposited on a rigid dielectric base. and an elastic dielectric film placed above it with strips of low-resistance material attached to its surface facing the flat zigzag and oriented parallel to the long sides of the flat zigzag. The step of laying the strips of low-resistance material is at least 2 times smaller than the step of laying the zigzag of high-resistance material. The measuring circuit can be made in the form of a four-arm resistive bridge, the constant resistors of which are placed on a common base with a high-resistance zigzag, forming an integral resistive element. FIG. 1 shows a resistive sensor, a longitudinal section; in fig. 2 is an integral resistive element of a device for measuring dimensions. The device contains a resistive sensor, made in the form of a flat U-shaped zigzag 1, deposited on a rigid dielectric base 2, and placed above it elastic dielectric film 3, on the inner surface of which, facing the flat zigzag, stripes 4 of low-resistance material are fixed. These low-level strips 4 are placed with a step a, which is at least 2 times smaller than a step d of zigzag 1 and arranged parallel to the long sides of this zigzag. Permanent resistors 5-7 are also placed on the dielectric base 2, which together with the flat zigzag form an integral resistive element — a pavement measuring circuit — the power supply is connected to one diagonal and the recording device is connected to the other (not shown). The controlled object 8 is placed in the process of measurement over the elastic dielectric film 3. A device for measuring the dimensions of flat surfaces works as follows. Under the action of the weight of the controlled object 8, elastic deformation of the dielectric film 3 occurs on its section corresponding to the area of the object. At the same time, strips 4 of low-resistance material shunt the corresponding sections of the long sides of the U-shaped zigzag 1, changing their total resistance. The number of shunted sections of high-resistance zigzag 1 is determined by the width, and the length of each shunt section is determined by the length of the object to be monitored in this area. In this case, the magnitude of the unbalance signal at the output of the measuring circuit will correspond to the controlled size of the surface of the object 8. This unbalance signal can be registered in light or printed form. The measurement error will not exceed 0.5 ° / o if the resistance of a unit of length of a high-resistance zigzag resistive sensor is not less than 200 times the resistance of a unit of length of low-resistance shunt strips. In order to reduce the systematic measurement error of the dimensions, the ratio of the lengths of the short and long sides of the U-shaped zigzag should be less than 0.1. Due to the possibility of fabricating a resistive sensor with small steps of laying low-resistance and high-resistance bands, especially with the integral design, measurement discreteness and greater accuracy are obtained when measuring the surface area of an arbitrary shape. Claim 1. Device for measuring the size of flat surfaces, containing a resistive sensor and measuring circuit, in order to improve the measurement accuracy and expand the range of monitored surfaces, the resistive sensor is made in the form of a flat U-shaped zigzag of high-resistance material applied rigid dielectric base, and an elastic dielectric film placed above it, with strips of low-resistance mat attached to its surface, painted to a flat zigzag Series oriented parallel to the long sides of the flat zigzag. 2. The device according to claim 1, characterized in that the step of laying the strips of low-resistance material is at least 2 times smaller than the step of laying the zigzag of high-resistance material. 3. The device according to paragraphs. 1 and 2, characterized in that the measuring circuit is made in the form of a four-arm resistive bridge, the fixed resistors of which are placed on a common base with a high-resistance zigzag, forming an integral resistive element. Sources of information taken into account during the examination 1. USSR author's certificate No. 195641, cl. G 01 D 5/16, 1965. 2. USSR author's certificate number 578561, cl. G 01 B 7/12, 1974. 4 1 fyg.1